1. Field of the Invention
The disclosed embodiments of the present invention relate to camera correction, and more particularly, to method and apparatus for tuning a camera correction setting (e.g., a shading correction setting or a white balance correction setting) for a camera module under a designated color temperature.
2. Description of the Prior Art
An electronic device (e.g., a mobile phone) may be equipped with a camera module such that a user can use the electronic device to take pictures. In general, the camera module includes a lens module and an image sensor module. The lens module is used to guide incident light onto the image sensor module. Hence, the quality of the lens module and/or the image sensor module would affect the image quality of the capture output of the camera module. For example, various imperfections in the lens module may create a lens shading effect. The lens shading effect may include luminance shading that causes brightness of the image center to differ from that of the image edges/corners. For an image sensor module designed to capture color images, the lens shading effect will have not only luminance shading but also color shading. Concerning the color shading, there will be a wavelength dependence of the shading such that different color components have somewhat different shading. If the image sensor module of the camera module has no built-in lens shading correction function, the inherent module variation cannot be suppressed. Even though the image sensor module of the camera module has a built-in lens shading correction function, the inherent module variation cannot be effectively suppressed due to the fact that the performance of the built-in lens shading correction function is generally poor.
Moreover, concerning the image sensor module, the sensor sensitivity of one color may be different from the sensor sensitivity of another color. Hence, a white balance correction function is required to make the captured image have correct colors. Specifically, the white balance correction is an adjustment that corrects for the color balance of the lighting so that white objects appear white, rather than colored, for example, yellow when lit by tungsten filament light or excessively blue under sunlight.
Thus, there is a need for an innovative camera correction and tuning design for avoiding/mitigating the image quality degradation resulting from imperfections of the camera module.